1. Field of the Invention
The present invention relates generally to a case for accommodating electronic equipment, and more particularly to a case for accommodating a hard disk drive (HDD) adapted to be removably mounted in a computer such as a server or a workstation.
2. Description of the Related Art
In recent years, it has been desired to reduce the size of an HDD as a kind of external storage device for a computer and also to increase the capacity of the HDD. A method for increasing the capacity of the HDD is to increase the number of magnetic disks to be mounted on a spindle. In a recent HDD, the spacing between disks to be mounted has been reduced with the increase in the number of disks. It is expected that a future HDD will have a higher capacity and a higher speed, so that there is a possibility that when a head mounted in a disk drive, tracing a certain track on a disk is minutely vibrated, the head may encroach on the adjacent tracks on the disk to cause off-track trouble such as data misreading or data garbling. This off-track trouble is also caused by vibrations of a spindle motor and other components mounted in the disk drive.
A host computer such as a server or a workstation is connected through a communication network such as a local area network (LAN) to many subordinate computers, and adopts a so-called active disk drive unit which can be easily inserted into and removed from a shelf for accommodating the disk drive unit in the condition where the power to the host computer is on. The active disk drive unit is composed of a disk drive such as a hard disk drive and a case for accommodating the disk drive therein. The active disk drive unit is inserted into or removed from the shelf accommodated in the host computer as required without powering off the host computer.
A conventional case for an active disk drive is formed of integrally molded plastic, and has a plurality of resilient portions. In the condition where the case accommodating the active disk drive is inserted in the shelf, the resilient portions of the case abut against guide rails formed on the inner surface of the shelf to thereby absorb the vibrations by utilizing a spring action of plastic. However, in such a conventional vibration absorbing method utilizing a spring action of plastic, the play of the active disk drive unit with respect to the guide rails of the shelf cannot be completely absorbed, and this play may amplify the vibrations of the head due to the vibrations of the spindle motor or a cooling fan in the computer. As a result, the head off-track trouble cannot be eliminated.